Radiography test system and method

ABSTRACT

A system and method for monitoring degradation of a device having a metal layer and a composite layer, such as a vehicle-mounted boom arm. The system can include a collar mounted on an outer surface of the device, a radiography device movably coupled to the collar, and a monitor. The radiography device can include a source of radiography signals positioned to direct radiography signals through at least a portion of the device and a detector to detect radiography signals that have passed through the device. The monitor can be connected to the detector to display an image of the device generated from the detected radiography signals. Anomalies in the device image can represent degradation in the device.

FIELD OF THE INVENTION

The invention relates to a system and method for non-destructiveexamination of degradation, such as corrosion and wear, on a non-visibleinterior of a device having a metal layer bonded to a composite layer,such as a vehicle-mounted boom arm.

BACKGROUND

Telephone and utility service providers frequently inspect or repairlines, trees, and other objects located at elevated heights. Boom armsfitted with baskets are commonly mounted to vehicles for elevatingpersonnel carried within the basket. Boom arms for such vehicles can beconstructed in a variety of configurations, including, for example, anover-center boom arm that can unfold from a horizontal position to avertical position.

Boom arms are typically hollow tubes that are strong and lightweightwith a multi-layer construction. One type of boom arm has an inner metallayer bonded to an intermediate composite layer (e.g., a steel portionthat extends 10 to 14 inches across a connection point betweenfiberglass portions). An outer layer is constructed of a protectivematerial, such as a gel-coat, and is bonded or applied over thecomposite layer.

The metal layer and the composite layer have different stiffnesses. Toprovide a smooth transfer of bending stresses created by the load in thebasket from the composite layer to the metal layer, the end of the metallayer is tapered over a region around the inner circumference of theboom arm. The tapered region allows a band of stress between the metallayer and the composite layer to dissipate. For example, the taperedregion diffuses the stress into a band having a width of about six toten inches. Without the tapered region, the stress would form a stressline, increasing the likelihood of failure of the composite layer.

The metal layer, and particularly the tapered region of the metal layer,is subject to degradation by, for example, corrosion or wear. Whencorrosion occurs, rust is produced and the thickness of the metalmaterial at the tapered region is reduced. Because the production ofrust does not occur uniformly, the remaining material at the taperedregion forms into peaks and valleys, increasing the magnitude ofstresses at stress points, rather than across a band. Rust is also worninto the composite layer adjacent to corrosion spots in the metal layer,eroding the composite material and reducing the strength of thecomposite layer. Finally, as metal and composite material at the taperedregion is depleted by degradation, gaps form between the composite layerand the metal layer, reducing the generally uniform transfer of stressesat the tapered region.

Each vehicle-mounted boom arm can be subject to different environmentalconditions depending on the use of the boom arm and the local climate.As a result, it is difficult to predict if and when degradation such ascorrosion and wear will occur. Furthermore, because degradation occurson the inside of the boom arm, there may not be any indicators ofcorrosion, erosion, wear etc. on the exterior or visible surface of theboom arm. In order to access the interior of the boom arm forexamination, the boom arm would have to be disassembled or evendestroyed with certain boom configurations.

SUMMARY

Accordingly, a need exists for a system and method of examiningdegradation, such as corrosion and wear, present on a non-visibleinterior of a device having a metal layer and a composite layer, such asa vehicle-mounted boom arm, without having to destroy or disassemble thedevice.

In one embodiment, the invention provides a method for non-destructivelyexamining degradation on an interior of a device having a metal layerand a composite layer. Radiography signals are directed through a regionof interest of the device, which includes the metal layer and thecomposite layer. Radiography signals that have passed through the deviceare detected. An image of the metal layer and the composite layer at theregion of interest is generated from the detected radiography signals.Anomalies in the device image representing degradation in the region ofinterest are identified.

In another embodiment, the invention provides a system fornon-destructively examining degradation on an interior of device havinga metal layer and a composite layer. The system includes a collar sizedand shaped to be mounted on an outer surface of the device, aradiography device movably coupled to the collar, and a monitor. Theradiography device includes a source of radiography signals arranged todirect radiography signals through at least a portion of the metal layerand the composite layer and a detector for detecting the radiographysignals. The monitor is connected to the detector to display an image ofthe device generated from the detected radiography signals.

In yet another embodiment, the invention provides a method formonitoring degradation on an interior of a device having a metal layerand a composite layer. A region of interest on an interior of the deviceis non-destructively examined for degradation, and the degradation isquantified. The device is placed in a first monitoring schedule ifsubstantially no degradation is present on the device. The device isremoved from service if a quantity of degradation in excess of adegradation threshold is present on the device. The device is placed ina second monitoring schedule if a quantity of degradation less than thedegradation threshold is present on the device.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a motorized vehicle with a boom arm in a foldedconfiguration.

FIG. 2 is a longitudinal cross-sectional view of a portion of a boomarm.

FIG. 3 is a lateral cross-sectional view of the boom arm of FIG. 2.

FIG. 4 is a perspective view of a radiography degradation detectionsystem according to one embodiment of the invention mounted to a boomarm.

FIG. 5 is a schematic view of a radiography degradation detection systemaccording to one embodiment of the invention operating on a boom arm.

FIG. 6 is an image of a portion of a tapered region of a boom arm withno degradation generated by a radiography degradation detection systemaccording to one embodiment of the invention.

FIG. 7 is an illustration of a portion of a tapered region of an actualboom arm having degradation.

FIG. 8 is an image of the portion of the tapered region of FIG. 7generated by a radiography degradation detection device according to oneembodiment of the invention.

FIG. 9 is an image of a portion of another tapered region havingdegradation generated by a radiography degradation detection deviceaccording to one embodiment of the invention.

FIG. 10 is a flowchart depicting a method of implementing a boom armdegradation monitoring plan according to one embodiment of theinvention.

FIG. 11 is a flowchart depicting a method of analyzing detectedradiography signals output from a radiography degradation detectiondevice according to one embodiment of the invention.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless specified or limited otherwise, theterms “mounted,” “connected,” “supported,” and “coupled” and variationsthereof are used broadly and encompass both direct and indirectmountings, connections, supports, and couplings. Further, “connected”and “coupled” are not restricted to physical or mechanical connectionsor couplings, and can include electrical connections or couplings,whether direct or indirect.

FIG. 1 illustrates a boom arm 10 mounted to a motorized vehicle 12 ofthe type commonly used to access elevated objects, such as power linesand trees. A first end 14 of the boom arm 10 is mounted to the vehicle12, while a second end 16 of the boom arm 12 is coupled to a passengerbasket 18. The boom arm 10 can include an elbow joint 20 so that theboom arm 10 can be stored folded into a horizontal or lengthwiseconfiguration while not in use, as shown in FIG. 1. The boom arm 10 canbe unfolded into a vertical position with the basket 18 elevated whilein use.

FIGS. 2 and 3 illustrate the construction of the boom arm 10, which is amulti-layer hollow, tubular member. This type of multi-layerconstruction may also be present in other types of devices or equipment,such as wire spreaders, cranes, platform lifts, cable placers, etc. Inthe electric utility industry specifically, composite materials are usedprimarily for construction in order to provide insulation from theelectric line voltages. Metals are generally only used to reinforce thejoints between composite structures. However, failure occurs at thesemetal-reinforced joints between composite structures. As shown in FIGS.2 and 3 for a vehicle-mounted boom arm 10, an inner layer 22 of the boomarm 10 is generally formed of a metal, such as steel. An intermediatelayer 24 of the boom arm 10 is generally formed of a composite material,such as fiberglass. An inner surface 25 of the composite layer 24 isbonded to an outer surface 27 of the metal layer 22 to secure the layersto one another. A tapered or transition region 32 is formed at an end 28of the metal layer 22, where the metal layer 22 is tapered from a firstthickness d₁ to a pointed or almost pointed edge 34 extending around thecircumference of the metal layer 22. However, the transition region 32may not be tapered in some boom arms. The composite layer 24 isgenerally longer than the metal layer 22, so that an end 26 of thecomposite layer 24 forms a tube extending beyond the end 28 of the metallayer 22. As shown in FIG. 5, an outer layer 36, such as a gel coat, ofthe boom arm 10 can be a protective coating formed or bonded to theintermediate layer 24.

FIG. 4 illustrates a radiography degradation detection system 50according to one embodiment of the invention mounted to boom arm 10. Thedetection system 50 can include a collar 52, a radiography device 54coupled to the collar 52, and a monitor 56 connected to the radiographydevice 54.

The collar 52 can be a ring-like member sized and shaped for mounting toan outside of the boom arm 10. An inner circumference c₁ of the collar52 can be slightly greater than an outer circumference c₂ of the boomarm 10. The collar 52 can include a hinge or other mechanism tofacilitate at least partially opening and mounting the collar 52 to theboom arm 10. The collar 52 can include a securing mechanism 62 to securethe collar 52 to the boom arm 10. The securing mechanism 62 can be aclamp, a compression collar, a magnet, bolts, etc.

In some embodiments, the collar 52 can include a track 64 along whichthe radiography device 54 can move. The radiography device 54 can becoupled to the collar 52 and can be moved around the circumference ofthe boom arm 10 by moving along the track 64. The radiography device 54can include a movement mechanism 65, such as a motor, for coupling theradiography device 54 to the collar 52 and for moving the radiographydevice 54 along the track 64. In one embodiment, the radiography device54 can be moved about 360 degrees along the track 64 in order to movearound substantially the entire circumference of the boom arm 10. Inanother embodiment, the radiography device 54 can be moved about 180degrees along the track 64 or about half of the boom arm circumference.

As shown in FIGS. 4 and 5, the radiography device 54 includes a source66 of radiography signals 67 and a detector 68 for detecting radiographysignals. In one embodiment, the radiography signals 67 are X-raysignals. The source 66 of radiography signals 67 and the detector 68 canbe spaced apart on the collar 52 and can be positioned so thatradiography signals 67 from the source 66 are directed into the boom arm10 through both the metal layer 22 and the composite layer 24 toward thedetector 68. The detector 68 can be positioned to detect radiographysignals 67 which have passed through the boom arm 10. The degradationdetection system 50 can be mounted to the boom arm 10 so that theradiography signals 67 pass through a region of interest of the boom arm10, such as the tapered region 32.

As shown in FIG. 4, the monitor 56 can generate and display an image ofthe interior of the boom arm 10 from the radiography signals detected bythe detector 68. The monitor 56 can be a handheld device, a personalcomputer, a laptop, or another suitable electronic device and caninclude a screen for displaying the image and/or data obtained from thedetected radiography signals. The detected radiography signals can bedisplayed as still images or can be displayed as a moving image as theradiography device 54 travels around the boom arm 10 along the track 64.The monitor 56 can display substantially all or a portion of thecircumference of the boom arm 10 at a given time. In one embodiment, themonitor 56 displays approximately an 11 degree arc of the boom arm 10circumference at a given time. The degradation detection system 50 caninclude a control mechanism 58 that controls movement of the radiographydevice 54, as well as overall operation of the degradation detectionsystem 50. The degradation detection system 50 can further includecables and connectors 60 for connecting the radiography device 54 to themonitor 56 and/or to other components of the degradation detectionsystem 50. The cables and connectors 60 can be replaced with a wirelessconnection.

FIG. 6 illustrates an image of the boom arm 10 of FIG. 2 generated bythe degradation detection system 50. An area 72 indicates the compositelayer 24, and is lighter than an area 74, because composite materials,such as fiberglass, tend to transmit more radiography signals. The area74 indicates the metal layer 22, and is darker than the area 72 becausemetal materials, such as steel, tend to block more radiography signals.A Demarcation line 76 between the area 72 and the area 74 corresponds tothe tapered region 32. As shown in FIG. 6, the demarcation line 76 is aclean, straight line. This mimics the straight edge 34 (as shown in FIG.2) and the uniform taper of the tapered region 32. In other words, thereis little or no degradation (see 82 in FIG. 6) in the tapered region 32of the boom 10. As used herein and in the appended claims, the term“degradation” refers to any type of corrosion, erosion, wear, loss ofmaterial, cracking, or any reduction in thickness, height, or width ofeither the metal layer 22 or the composite layer 24 of they boom arm 10.

FIG. 7 illustrates a portion of a boom arm 10 a in which the transitionregion 32 a has experienced degradation, including corrosion of themetal layer 22 that has formed rust 80 a. FIG. 8 illustrates an image ofthe boom arm 10 a of FIG. 7 generated by the degradation detectionsystem 50. The demarcation line 76 a from the area 74 a (representingthe metal layer 22) to the area 72 a (representing the composite layer24) is jagged and fuzzy in comparison to the clean demarcation line 76in FIG. 6. This is caused by variations in thickness of the compositelayer 24 and/or the metal layer 22 due to degradation. In addition, atleast a first anomaly 82 a is formed in the area 74 a representing themetal layer 22, which indicates an area of reduced thickness of themetal layer 22, the composite layer 24, or both. Such lighter shading onthe image for an area representing a given material is caused by anincrease in detection of radiography signals at the detector 68, whichin turn indicates a reduced thickness of the material relative to thesurrounding material. This applies to both the metal layer 22 and thecomposite layer 24. As a result, there is significant degradation in thetapered region 32 of the boom 10 a, which could lead to failure of theboom 10 a.

FIG. 9 is another image of a portion of a boom arm 10 b illustrating ananomaly 82 b in area 74 b. In contrast to the anomaly 82 a shown in FIG.8, anomaly 82 b does not occur at the demarcation line 76 bcorresponding to edge 34 of the tapered region 32, but is within thetapered region 32. The demarcation line 76 b is still relatively cleanand straight compared to FIG. 8. However, there is some degradation inthe tapered region 32 of the boom 10 b.

Jaggedness or fuzziness of the demarcation line 76, spots of lightershading in either the metal area 74 or the composite area 72, and otherphenomena collectively form anomalies in the image of the boom arm 10.Such anomalies mimic the geography of degradation, such as corrosion ofthe metal layer 22 and erosion of the composite layer 24. Thus, thedetected radiography signal image generated by the monitor 56 provides avisual indication of degradation in the interior of the boom arm 10 thatclosely corresponds to actual degradation present on the boom arm 10.

The degree of degradation, or reduced thickness of one or more of thelayers of the boom arm 10, can be indicated by the shading of theanomalies. A substantially lighter anomaly indicates more degradationand more reduced material thickness, while an anomaly that is onlyslightly lighter indicates less degradation and less reduced materialthickness. Thus, the detection system 50 can identify degradationpresent on the boom arm 10, and in some embodiments, can quantify thedegree or amount of degradation by relating shading of anomalies in theimage to loss of material thickness. A surface area of degradation canbe determined from the area of anomaly locations. The extent ofdegradation can be categorized and quantified in a number of ways,including, for example, reduction in material thickness, surface area ofdegradation, surface area of degradation relative to the surface area ofthe tapered region 32, number of degradation/anomaly locations, etc.

In one embodiment, visual analysis of the image of the boom arm 10 onthe monitor 56 is used to identify and/or quantify degradation of theboom arm 10. This analysis can be performed manually by the operator ofthe degradation detection system 50 upon viewing the image on themonitor 56. In other embodiments, a software program, image analysistool, or other computerized device can be used to automatically analyzethe image of the boom arm 10 to identify and/or quantify degradation. Instill other embodiments, a software program, signal analysis tool, orother computerized device can be used to analyze not the image, but thedetected radiography signals themselves, in order to identify and/orquantify degradation. Such computerized devices can be installed on ahandheld device, laptop, or personal computer that is connected to themonitor 56 and/or the radiography device 54, or can be integrated intothe monitor 56. The results of the analysis by the computerized devicecan be displayed on the monitor 56 or another suitable display device.In addition, such data can be archived, uploaded to a database,transmitted to another party, etc. Finally, in some embodiments, eventhough identification and quantification of degradation can be carriedout automatically by a computerized device, the images of the boom arm10 can also be displayed on the monitor 56 for visual review by theoperator of the degradation detection system 50.

FIG. 10 is a flowchart illustrating a method for monitoring degradationof a boom arm. The method can be used to monitor the degradation of, forexample, a fleet of vehicle-mounted boom arms. The degradation detectionsystem 50 is mounted (at 110) to the boom arm 10 at a region of interestof the boom arm 10, such as the tapered region 32. The degradationdetection system 50 is operated to direct (at 120) radiography signalsthrough the region of interest and to detect radiography signals thathave passed through the region of interest. The radiography device 54 ofthe degradation detection system 50 can be rotated around substantiallyall or a portion of the boom arm 10. The detected radiography signalscan be analyzed (at 130) to determine if degradation is present on aninterior of the boom arm 10. This analysis can be carried out byvisually inspecting an image of the boom arm 10 on the monitor 56,through the use of a computerized device to analyze the detectedradiography signals or image, or a combination of both.

FIG. 11 is a flowchart illustrating a method of analyzing detectedradiography signals (as at 130 in FIG. 10) to determine if degradationis present. In some embodiments, an image of the boom arm 10 isgenerated from the detected radiography signals (at 131). A computerizeddevice can automatically analyze the image or the radiography signaldata to determine how many dark pixels (representing the metal layer 22)versus light pixels (representing the composite layer 24) are present(at 132). The computerized device can compare the number of dark pixelsand/or light pixels to how many dark pixels and/or light pixels thereshould be on a boom arm 10 without any significant or hazardousdegradation. The computerized device can also compare the number of darkpixels and/or light pixels to dark and/or light pixel thresholds (at 133and 135). If the light pixel threshold is exceeded (i.e., there are toomany pixels representing composite material or reduced materialthickness in the image or data), the computerized device can generate anoutput indicating that the metal layer 22 has been degraded and that theboom arm 10 should be retired or repaired (at 134). Similarly, if thedark pixel threshold is not exceeded (i.e., there are not enough pixelsrepresenting metal material or sufficient material thickness in theimage or data), the computerized device can generate an output alsoindicating that the metal layer 22 has been degraded and that the boomarm 10 should be retired or repaired (at 137). If the light pixelthreshold is not exceeded and the dark pixel threshold is exceeded, thenthe computerized device can generate an output indicating that there isno degradation on the boom arm 10 and the boom arm 10 can be returned toservice (at 136). In some embodiments, based on the number of pixels andthe comparison to one or more pixel thresholds, the computerized devicecan generate a definitive output that can be used by personnel toconsistently categorize boom arms as being “acceptable”, “of interest”,or “non-acceptable”, as further described below.

Returning to FIG. 10, if no degradation is detected on the boom arm 10,the boom arm 10 is categorized (at 140) as “acceptable”. The“acceptable” boom arm 10 can remain in service and can be placed (at150) into a first or routine monitoring schedule. The first monitoringschedule can, for example, provide for annual degradation tests. Ifdegradation (such as corrosion, wear, or erosion) is detected on theboom arm 10, the extent of the degradation can be compared (at 160) to adegradation threshold. If the detected degradation exceeds thedegradation threshold, the boom arm 10 can be categorized as“non-acceptable” (at 170) and can be removed (at 180) from service forretirement or repair. If some degradation is detected, but the extent ofthe degradation does not exceed the degradation threshold, the boom arm10 can be categorized (at 190) as “of interest”. The “of interest” boomarm 10 can remain in service and can be placed (at 200) into a second oraccelerated monitoring schedule. The second monitoring schedule canprovide for more frequent, subsequent degradation tests than the firstmonitoring schedule. The second monitoring schedule can, for example,provide for biannual degradation tests.

The monitoring schedule scheme can vary widely. For example, “ofinterest” boom arms can be tested every three months on the secondmonitoring schedule, while “acceptable” boom arms can be tested everysix months on the first monitoring schedule. Intermediate degradationthresholds can be used to place the boom arm among multiple “ofinterest” categories with varying monitoring schedules. The calendar forboth routine and accelerated testing schedules can be based in part onthe climate in which the boom arm has been or will be located. Forexample, boom arms located in climates of high humidity and rainfall(such as Florida) can be tested every six months for “acceptable” boomarms and every three months for “of interest” boom arms, while boom armslocated in arid climates (such as Arizona) can be tested every year for“acceptable” boom arms and every six months for “of interest” boom arms.In this manner, the testing method of FIGS. 10 and 11 can be applied toa nationwide or global fleet or stock of boom arms.

The degradation threshold can also vary widely. In one embodiment, thedegradation threshold is 1/16 inch. A reduction in height (or a holeinward from the edge of the layer) in the either the metal layer 22 orthe composite layer 24 of up to 1/16 inch can cause the boom arm to beis categorized as “of interest” and a reduction in height (or a holeinward from the edge of the layer) greater than 1/16 can will cause theboom arm to be categorized as “non-acceptable”. In another embodiment, areduction in thickness of either the metal layer 22 or the compositelayer 24 up to 5% of the initial thickness is categorized as “ofinterest” and a reduction in thickness of greater than 5% is categorizedas “non-acceptable”. Such degradation thresholds can be dependent uponthe initial thickness of the metal layer 22 and the composite layer 24and/or the material characteristics of the metal layer 22 and thecomposite layer 24. Furthermore, a first degradation threshold can beapplied for reductions in thickness of the metal layer 22 and a seconddegradation threshold, different from the first degradation threshold,can be applied for reductions in thickness of the composite layer 24.Such degradation threshold limits can also be dependent upon theintended use of the boom arm 10 or a maximum load that can be carried inthe basket 18.

The foregoing discussion of degradation threshold assumes thatdegradation will be quantified in terms of loss of material. In otherembodiments, degradation can be quantified in terms of total surfacearea of degradation, relative surface area of degradation, total numberof degradation locations, or other suitable factors. Degradationthresholds for the purposes of boom arm categorization can be selectedaccordingly. In one embodiment, for example, a boom arm determined tohave a total surface area of degradation up to 1 cm² is categorized as“of interest” and a boom arm having total surface area of degradationgreater than 1 cm² is categorized as “non-acceptable”.

Thus, the invention provides, among other things, a system and methodfor non-destructive examination of degradation on an interior of a boomarm. Various features and advantages of the invention are set forth inthe following claims.

1. A method of non-destructively examining degradation on an interior ofa device having a metal layer bonded to a composite layer, the methodcomprising: directing radiography signals through a region of interestof the device, the region of interest including the metal layer and thecomposite layer; detecting radiography signals that have passed throughthe device; generating an image of the metal layer and the compositelayer at the region of interest from the detected radiography signals;and identifying degradation in the region of interest from the image. 2.The method of claim 1 wherein the region of interest is a tapered end ofthe metal layer.
 3. The method of claim 1, wherein the degradationrepresent a reduction in thickness of at least one of the metal layerand the composite layer.
 4. The method of claim 1 further comprisingquantifying the degradation from at least one of the image and thedetected radiography signals.
 5. The method of claim 1, whereinidentifying degradation in the image further comprises: determining anumber of pixels in the image, the pixels including light pixels anddark pixels; and comparing the number of at least one of the lightpixels and the dark pixels to a threshold.
 6. A method of monitoringdegradation on an interior of a device having a metal layer and acomposite layer, the method comprising: non-destructively examining fordegradation a region of interest on an interior of the device includingthe metal layer and the composite layer; quantifying the degradation;placing the device on a first monitoring schedule if substantially nodegradation is present on the device; removing the device from serviceif a quantity of degradation in excess of a degradation threshold ispresent on the device; and placing the device on a second monitoringschedule if at least some degradation, but less than the degradationthreshold is present on the device.
 7. The method of claim 6, whereinthe second monitoring schedule includes more frequent examinations fordegradation than the first monitoring schedule.
 8. The method of claim6, wherein at least one of the first monitoring schedule and the secondmonitoring schedule is selected based upon a climate region in which thedevice is located.
 9. The method of claim 6, wherein the degradationthreshold is selected based upon an initial thickness of at least one ofthe metal layer and the composite layer.
 10. The method of claim 6,wherein the degradation is quantified as a loss of thickness of at leastone of the metal layer and the composite layer.
 11. The method of claim6, wherein the region of interest is a tapered end of the metal layer.12. The method of claim 6, wherein non-destructively examining theregion of interest of the device comprises: directing radiographysignals through the region of interest of the device; detectingradiography signals that have passed through the device; generating animage of the metal layer and the composite layer at the region ofinterest from the detected radiography signals; and identifyinganomalies in the image representing degradation in at least one of themetal layer and the composite layer.
 13. The method of claim 6, whereinnon-destructively examining the region of interest of the device furthercomprises: directing radiography signals through the region of interestof the device; detecting radiography signals that have passed throughthe device; generating an image of the metal layer and the compositelayer at the region of interest from the detected radiography signals,the image including light pixels and dark pixels; determining the numberof at least one of the light pixels and the dark pixels present in theimage; comparing the number of the one of the light pixels and the darkpixels to a threshold; and determining whether degradation is presentbased on the comparison between the number of the one of the lightpixels and the dark pixels and the threshold.
 14. A non-transitorycomputer readable medium having computer readable instructions storedthereon for execution by a processor to perform a method fornon-destructively examining a device for degradation comprising:detecting radiography signals directed through a region of interest ofan interior of a device having a metal layer and a composite layer;generating an image of the metal layer and the composite layer at theregion of interest from the detected radiography signals; andidentifying anomalies in the image representing degradation in at leastone of the metal layer and the composite layer.
 15. The computerreadable medium of claim 14 wherein the step of generating an imagecomprises generating light pixels and dark pixels corresponding to thedensity of the material being examined; and the step of identifyinganomalies in the image comprises determining the number of at least oneof the light pixels and the dark pixels present in the image; comparingthe number of the one of the light pixels and the dark pixels to adegradation threshold; and determining whether degradation is presentbased on the comparison between the number of the one of the lightpixels and the dark pixels and the degradation threshold.
 16. Thecomputer readable medium of claim 14 wherein the degradation thresholdis selected based upon an initial thickness of at least one of the metallayer and the composite layer.
 17. The computer readable medium of claim14 wherein the degradation is quantified as a loss of thickness of atleast one of the metal layer and the composite layer.
 18. The computerreadable medium of claim 14 wherein the region of interest is a taperedend of the metal layer.